Level of nicotine dependence is widely regarded as an important predictor of smoking cessation outcome, yet a nicotine dependence measure with proven validity and clinical utility has not been available. Results from a pilot study strongly indicated the potential value of an initial core of items (based on psychoactive substance abuse criteria applied to nicotine) as a means for improving understanding and measuring the nicotine dependence construct. The treatment and theoretical benefits of such an instrument prompt us to advance our pilot work towards a multidimensional measure of nicotine dependence with demonstrated validity and reliability that will also be easy to administer by both the self-report and the interview method. The proposed study will be conducted in two phases. In phase one, item construction and refinement. our aims are: 1) to write multiple sets of multiple items to operationally define several hypothetical constructs comprising the nicotine dependence syndrome and 2) to construct an interview/self-rating protocol. i.e. the Nicotine Dependence Scale (NDS). in phase two, a field test of the NDS, our aims are: 1) to use exploratory factor analysis to identify the underlying constructs amongst a total set of approximately 80 items. 2) to determine through confirmatory analysis the invariance of the identified factor structure across demographic and psychological subgroups, 3) to determine internal consistency and re-test reliability, 4) to estimate the ability of the total NDS score and the battery of factor scored variables, singly and in weighted linear combination, to predict smoking cessation outcome, 5) to estimate the association of the total NDS score and the underlying factor scores with such variables as number of cigarettes smoked daily number of past attempts to stop smoking, carbon monoxide level, and the Fagerstrom Test score. Subjects will be smoking cessation program participants from the American Cancer Society in New Yore City (n=600) and from the Veterans Administration Hospital in Loma Linda, California (n=200). Approximately 60% of ACS subjects and 5% of VA subjects will be females; about 15-20% in both sites will be nonwhite. The high cost of chronic tobacco use (it is the leading cause of death among US adults) warrants efforts aimed at improving cessation techniques. Increased understanding of and ability to measure the nicotine dependence construct is an essential part of that task.